The present invention relates to remote operated vehicles or ROVs, and in particular to ROVs for use in exploration of an underwater environment.
Conventional ROVs are typically used by commercial enterprises and comprise a “submarine” unit or vehicle (the fish), a landbased remote control unit (the topside) connected to a power source such as a generator or power cells, and an umbilical cable connecting the two units together for transmitting power and control signals from the topside to the fish.
The fish is usually fitted with swimming means, such as motor driven propellers, for maneuvering the fish underwater, and a camera, typically a video camera. Images from the camera can be transmitted from the fish, along the umbilical cable, to the topside for displaying on a monitor or viewfinder attached to the topside. Stills cameras may also be fitted onto the fish allowing more detailed images, i.e. at higher resolutions, to be taken. Other information may also be sent along the cable, such as speed or headings.
The topside is used to transmit control signals down the umbilical cable to the fish for controlling the thrusters and any accessories, or options, such as hydroplanes or grabbers, such as those on arms having gripping means for picking up articles on the seabed, or possibly a pan or tilt mechanism fitted to the camera. It can also be used to transmit power simultaneously.
Commercial ROVs are generally very massive, and therefore cannot be transported from location to location by a single person. They are usually moved by crane onto a ship and are used, for example, for the inspection of subsea pipes and cables. Their large size, and cost, has hindered the development of the use of ROVs for recreational purposes, such as exploring reefs or checking the visibility at a dive sight such as a wreck before incurring diver downtimes. It would therefore be desirable to provide an ROV that can easily be transported by a single person for recreational use.
Small and lightweight ROVs have been recently developed by VideoRay Inc. such as the VideoRay 2000 ROV unit, designed for recreational use. The fish is sufficiently small and lightweight to be carried by one person. However, even with a smaller fish, the power supply together with the umbilical cable for transmitting the power from the surface to the fish are still difficult to manhandle.
According to a first aspect of the present invention, there is provided an ROV comprising a topside, a fish and an umbilical cable for connecting the topside and the fish together, wherein the fish is adapted to be powered by an onboard power supply, the cable has an outer skin and a control-signal carrying core, the core of the umbilical cable having a diameter of less than 2 mm along a substantial portion of the cable's length.
The onboard power supply is preferably in the form of a removable, water-sealed battery. The battery may be fully electrically-insulated. Non-contact coupling means, e.g. reactive coupling such as inductance or capacitance couplings, can be used to extract power from the battery without any need for direct electrically conducting contact means between the battery pack and its adjacent components. Preferably the coupling is by means of inductance coupling.
According to a second aspect of the present invention there is provided an umbilical cable for an ROV for carrying signals between a topside and a fish of the ROV, the fish requiring an onboard power supply, the cable having an outer skin and a control-signal carrying core, wherein the core has a diameter of less than 2 mm along a substantial portion of the cable's length.
Preferably, the diameter is 1.2 mm. Preferably, the core of the cable is a coaxial cable. Coaxial cables allow the transmission therealong of information by frequency division multiplexing, for example RF transmissions. Such transmissions allow a large quantity of information, such as TV, to be transmitted over distances, down fine cables. Therefore, transmission of not only control signals therealong to the fish, but also return signals from the fish to the topside such as video signals can be achieved. However, high power loads such as those required to drive the thrusters on the fish will not be transmittable, other than at very high voltages.
Preferably, the core of the cable is surrounded by linear fibers of a high tensile strength, flexible material, such as Dynema® or Kevlar®. Preferably, the cable comprises a highly buoyant skin to give the cable a positive buoyancy. Preferably a hairy polypropylene braid surrounds the cable. This braid can reduce the drag of the cable through water.
In accordance with another aspect of the present invention, there is provided a fully water-sealed and electrically-insulated battery pack for fitting in or onto an in- or an under-the-water, electrically operated device.
Since the main power for an ROV of the present invention, in use, is carried onboard the fish, there is no need to transmit substantial power down the umbilical cable to the fish. The only energy to be transmitted down the umbilical cable is control signals, e.g. for instructing a control processor provided on the fish for controlling the fish's thrusters, cameras or other accessories.
Preferably, the ROV is fitted with an onboard video camera for streaming video images to the topside. This enables the use of the ROV in providing an “underwater experience”, for example via a virtual reality headset. The video images will be transmitted on the umbilical cable from the fish to the topside.
Another aspect of the present invention is the provision of an ROV that has two cameras, one mounted at the front of the fish, the pan and tilt thereof preferably being adjustable for viewing in variable directions underwater, and the second camera being provided in a “periscope” position. Preferably the periscope camera is fitted above the main body of the fish. However, it may also be indirectly positioned in such a position by the provision of periscopic mirror arrangements. The periscope camera can provide, for example, either an alternative view in the water, or, at the water surface, an above-the-water view, for example to assist in directing the fish back to land or to the controller, or to a partially submerged object to be viewed. Pictures from the cameras can be transmitted on the umbilical cable to the topside. However, when the communication system between the fish and the topside cannot handle two video channels, then means for selecting which camera is active can be provided.
The first camera could be a color camera and the second camera could be a monochrome camera, such as a black and white camera. The monochrome camera will generally provide better low-light capabilities than the color camera due both to its conventionally higher resolution, and its adaptability for low-light sensitivity, for example due to its intrinsic higher sensitivity, or by the provision of image intensifying means. Low light sensitivity will allow use of the ROV in reduced light environments such as at depths where the ambient light has been filtered out by the water, or at twilight. Low light capabilities also remove the need continuously to burn lights provided on the fish, e.g. for battery saving purposes.
Another aspect of the present invention is the use of non-contact coupling techniques to transfer power for driving electric components on an underwater device from a water and electrically sealed circuit to a separately water and electrically sealed electric circuit. For example, the primary and ancillary components on a fish of an ROV, such as motors (or thrusters), cameras, illumination devices, and an onboard computer could be powered by induction coupling power from an onboard water and electrically sealed battery. Induction coupling could also be used to transmit the control signals between an umbilical cable and a fish of an ROV through a water and electrically sealed bulkhead.
Preferably, the non-contact power coupling means is inductive, but alternative indirect electrical coupling techniques include optical emitters and receptors or electrostatic transfers across adjacent capacitance plates.
The fish may be provided in modular form, having a number of locations provided about its form for attachment of ancillary components. Each position may be provided with a non-contact communication and power point.
Preferably, for an inductive coupled power point, twin opposed pairs of windings are provided on outer limbs of an E shaped magnetic core and a third coil is provided on the central limb. Induction coupling using this arrangement allows two independent power takeoffs to be obtained at a single point. For example, motor power, which required a high load variable power induction coupling, and a computer's power, which requires a lower load continuous power induction coupling, can be operated simultaneously from a single power source at a single induction coupler point, independently of each other. A number of induction coupler points may be provided on the power supply so that many components can be driven by the power supply simultaneously, but independently of each other.
Multiple point safety interlocks may be provided between the two circuits, i.e. the main body of the fish and its battery or ancillary components, so that the induction points are turned on and off upon fitting or removing either the battery or, optionally, the ancillary components (i.e. options) to or from the fish. This prevents the magnetic core remaining “live” unnecessarily; high power magnetic fields may be hazardous if not contained in a magnetic core.
According to a further aspect of the present invention, there is provided a topside for instructing a fish of an underwater ROV, the topside comprising a wireless handset and a computer unit, the computer unit, in use, being adapted to instruct the fish via an umbilical cable connected to the fish and the computer unit, and the wireless handset being adapted to transmit user defined instructions to the computer unit. This allows a user to roam around the computer unit, within the range of the transmitting means of the handset, or for the handset to be passed between a number of users without a cable connecting the handset to the base unit getting in the way. The computer unit may have a winder attached to it for managing the umbilical cable.
According to a further aspect of the present invention, there is provided a fish for an ROV of the type having a umbilical cable connecting the fish to a topside, the fish being provided with twin, side-mounted, horizontal thrusters, wherein the fish is provided with a position for connecting the umbilical cable thereto at a location directly at or substantially above the mid-point of a line between the twin thrusters. The positioning of the cable attachment position at or directly above such a point prevents any tension from interfering with the directional control of the fish.
According to another aspect of the present invention, there is disclosed a waterproof cable connector for fitting within an aperture in a pressure wall, the connector having an outer sleeve of a size substantially corresponding to, but slightly smaller than, the size of the aperture, and an epoxy filled core supporting the cable to be extended through the pressure wall within the sleeve, the sleeve having two pressure resisting flanges thereon, one for engaging against an outer surface of the pressure wall adjacent the aperture, and one extending radially inwardly from the inner surface of the sleeve for resisting movement of the epoxy when under pressure. The juncture between the epoxy and the second flange may be provided by a pressure resistant planar barrier.
In commercial underwater ROVs, if the fish gets in trouble, for example due to tangling of the umbilical cable about an underwater obstruction, it is necessary for the umbilical cable to be manually released from the fish by a diver. This would be impractical for recreational ROVs since the user would not necessarily have diving equipment. Therefore, according to a further aspect of the present invention, there is provided a release mechanism for the cable for use on an underwater ROV. Preferably, the self popping release mechanism can be activated by the user from the topside. However, the mechanism could also be programmed to release if the umbilical cable snaps. A spring-loaded cable release mechanism may be needed to allow the cable to be released when under tension, for example in a fast water current.
The ROV could log its movements on a particular dive so that it could automatically seek its way back substantially to its starting point upon cable disconnection. For example, ultrasonic locators could be fitted for sensing the fish's position relative to an object in the water, or the seabed.
According to a further aspect of the present invention there is provided a fish for an ROV comprising a camera and a window for the camera, wherein the window is a dual layer window, the first layer, internal of the second window, being sealingly mounted over the camera lens to prevent, in use, water ingress to the camera, and the second layer being positioned over the first window, being adapted to allow flooding of the space between the two layers. The first layer provides at least a part of the pressure housing over the camera. The second layer provides a protection layer for the first layer to prevent the first layer being scratched. Under high pressure, a scratch in the first layer would increase the probability of the layer failing. However, the second layer, is pressurized on both sides due to it being flooded, i.e. under a pressure equilibrium.
The fish of the present invention may be provided with a hydrophone to enable marine sounds to be observed.
A further aspect of the present invention is an underwater communications device comprising a send and receive communications processor and a handset, wherein using the handset, a short text message can be written and transmitted to the communications processor for sending out ultrasonically to a message recipient. The communications processor may be onboard the handset or a fish of an ROV. Two handsets may be provided, each with a send and receive communications processor so that two divers can communicate with each other underwater. The communications device may also be used to enable communication between the diver and the fish, the diver and the topside and the diver and the surface. The communications processor, when provided in the fish, may transmit the message along the umbilical cable. The handset may be in the form of a keypad on the fish, or a wireless handset, and can comprise a screen or a speaker for showing or relaying the message in the water.
The fish may be provided with an onboard computer that automatically corrects any yaw of the fish caused by water currents or drifts dragging the cable. Sensing devices or means could be by way of compass or inertial devices fitted to the fish, which are adapted to inform the computer of the fish's heading, acceleration and speed. The yaw control may alternatively be provided by the topside.
The fish may be provided with a depth-sounder, e.g. to allow fixed height swimming of the fish from the seabed or below the water's surface. Alternatively, the sensing could be horizontal, or in other directions, for allowing the maintenance of the fish at a minimum distance from an object.
Preferably, the onboard power supply of the fish is positioned on the underside of the fish so that it acts as a ballast weight. Further, three feet may be provided on the top of fish so that by inverting the fish onto the three feet, the fish is maintained by the feet in an appropriate position to facilitate mounting or dismounting of ancillary components or the battery pack or power source to or from the fish.
According to a further aspect of the present invention there is provided a pan and tilt mechanism for a camera comprising an arcuate drive bolt fixed relative to a chassis of the mechanism and a pivotable gimbal for mounting the camera thereon, wherein a lead nut mounted to the gimbal can be moved along the bolt to pivot the gimbal. A potentiometer may be operatively connected to the gimbal for detecting the angle about which the gimbal is pivoted.
According to a further aspect of the present invention, there is provided a motor for an ROV thruster, the motor comprising a fixed stator having electromagnet coil windings on core fingers thereof, the stator being positioned within a pressure housing about which is mounted a sealed rotor having permanent magnets and propellers, wherein water is free to circulate between the rotor and the pressure housing.
According to a further aspect of the present invention there is provided a hand controller for an ROV with left and right side thrusters and a vertical thruster, the hand controller comprising: a handle portion shaped for gripping between the fingers and palm of either a left or a right hand; and a first controller mounted for thumb actuation by the gripping left or right hand and configured to provide control signals for a left thruster and a right thruster of the ROV, thereby to control surge and yaw.
The first controller may be further configured to provide control signals for a vertical thruster of the ROV, thereby to control heave.
The hand controller in an embodiment comprises a second controller mounted for index finger actuation by the gripping left or right hand and configured to provide control signals for a vertical thruster of the ROV, thereby to control heave. The second controller may comprise first and second actuation elements for initiating up and down heave motion.
The hand controller preferably comprises a wireless transmitter for transmitting the control signals to a control unit. Alternatively a cable connection between the hand controller and the topside computer unit could be provided.
In an embodiment, the first controller is a joystick. Alternatively, a trackball or other multidimensional manually actuatable input device could be used.
The hand controller may further comprise a camera controller mounted for actuation by another hand and configured to provide further control signals for panning and tilting a camera in the ROV. The hand controller may also further comprise a light controller mounted for actuation by another hand and configured to provide further control signals for switching on and off at least one light in the ROV.